Diffusion and Osmosis

Diffusion Solute molecules moving from an area of high concentration to an area of low concentration Random motion drives diffusion Movement is based on kinetic energy (speed), charge, and mass of molecules Equilibrium is reached when there is an even distribution of solute molecules (water) 2 3 1 4

Cell Membrane Semipermeable - Some things can get through and some things cannot

Why is the cell membrane semi-permeable? To complete necessary functions in the cell: Bring oxygen into the cell, and remove carbon dioxide. Brings water into the cells. Removes waste from cells. Prevents some things from coming into the cell.

Osmosis Diffusion of water through a semi-permeable membrane Semi-permeable: permeable to solvents (WATER), but not to large molecules High [water] to low [water]

Osmosis Dissolved molecules (i.e. glucose, starch) are called solutes REMEMBER: Water = solvent Glucose, Starch = solutes

Hypertonic- means water moves from the cell to the environment

Isotonic- means water moves equally between the cell and the environment

Hypotonic – means water moves from the environment to the cell

Osmosis in Living Cells Cellulose in cell wall

Movement of Substances across Cell Membranes Cell membrane – dual function Stops some materials Allows exchange of other materials

Transportation of Molecules Passive Transport Does not require energy follows the concentration gradient from high to low

Transportation of Molecules Active Transport Needs energy to move particles Moves against the concentration gradient from low to high

% H2O 10% Solute 10% solute

% H2O 40% Solute 10% solute

% H2O 10% Solute 40% solute

Photosynthesis The process in which plants use sunlight to convert carbon dioxide and water into oxygen and glucose (sugar).

Respiration C6H12O6 + 6O2 6CO2 + 6H2O + released energy The process in which animals and plants use oxygen and glucose to release energy and release water and carbon dioxide.